The invention relates to a motor vehicle having an internal combustion engine, a transmission, and a conventional flywheel, and which in addition to the customary clutch between the flywheel and transmission, has a second, controllable clutch between the engine and flywheel. A motor vehicle of this type is disclosed in U.S. application Ser. No. 955,186, filed Oct. 27, 1978 now U.S. Pat. No. 4,252,208. By selective actuation of the second clutch, the engine can be disconnected from the drive train and stopped during periods of vehicle travel when the engine is not required to power the vehicle. The flywheel is normally provided for equalizing the non-uniformities of engine torque, and when disconnected from the engine the engine stalls. During such operating states when the engine is stopped, kinetic energy is stored in the flywheel and is used to restart the engine when desired.
By way of example, the engine and flywheel may be disconnected and the engine stopped when the vehicle is deaccelerating or idling, as long as the flywheel rotates above a minimum rpm. When the number of rotations of the flywheel tends to fall below the minimum rpm, or the engine is required again to accelerate the vehicle, the connection between the motor and flywheel is automatically restored, and the stored kinetic energy in the flywheel rotates the engine crankshaft causing the engine to restart. The periodic stoppage of the engine, during operating states when not required, results both in decreased per mile fuel consumption of the vehicle, and lower per mile emissions.
The present invention also relates to an improved starter and generator arrangement for an internal combustion engine.
In conventional motor vehicles, the generator is spacially and functionally separate from the starter motor of the engine. The generator is normally connected to a rotating shaft of the engine by a V-belt to be run off the engine. On the other hand, due to the high start-up torque necessary to turn over the engine, the starter motor is normally arranged to engage directly the engine, e.g. by a gear arrangement, during start-up. German Pat. No. 932,334, however, discloses a starting device in which the starting motor and engine generator have been combined. The rotor of the combined starter and generator is provided with an electrical winding and supported rotatably on an extension of the engine crankshaft by anti-friction bearings. The cooperating stator surrounds the rotor and is fixed on a cylindrical prolongation of the engine housing surrounding the crankshaft extension. The rotor and stator assembly is enclosed in a dish-shaped inertial clutch assembly including an inertia flywheel attached to the rotor and a clutch element positively connected with the rotor and engaging the inertia flywheel.
It has also been proposed to use a starting motor with a windingless rotor in an internal combustion engine, as, for example, shown in German Auslegeschrift No. 21 23 831. The rotor is provided in the form of a rim attached to the flywheel. As in the case of the apparatus disclosed in German Pat. No. 932,334, in the starter motor arrangement provision must be made to deliver the high start-up torque needed to rotate the entire crankshaft mechanism of the engine. In addition, the starter motor of the German Auslegeschrift No. 21 23 831 must, during cranking, drive the customary generator (coupled separately to the engine).